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Discussion Starter #1
My 03 crew cab short box 2wd Duramax ZF 6-speed truck has a shudder when I get on the gas. I'm pulling a 9000# trailer and was running a box in the over 100 hp range. (It's a test mule box and doesn't have different settings) When the box is disconnected there's no problem. With the box connected and no trailer there's no problem. Two questions: First is it the dual mass flywheel bottoming its springs or is it the driveline? I'm inclined to think its drive line. Some clutch guys have told me a dual mass does bottom when ever you trounce the gas. Second, Is my ZF truck covered under the one piece drive shaft TSB?
 

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No so Eric. My '03 has the ZF and a 2 piece drive shaft.


Is there a length difference between the ZF and the Allison? Could that be the reason for the 2 piece shaft?


Later...
 

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JMPDMAX,


I've got a 2003 GMC Sierra Duramax with a ZF6 speed and a ONE piece drive shaft. Don't know what the diff is but only that mine is a one piece.


Steve


Oh yeah on edit Mine is a Xtened cab. Will edit sig. Thanks.....


Edited by: bigsky1
 

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crew cab vs extended cab?

My '02 CC LB 4x4 has a 2-piece, no issues.
 

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ZFMax said:
crew cab vs extended cab?

My '02 CC LB 4x4 has a 2-piece, no issues.

That's probably it. My '03 is a Crew Cab also..


I've updated the sig to show it now....


Later....
 

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Discussion Starter #7
I talked to one of the few people making a clutch for our truck (I don't remember the name but they make a kevlar and also a ceramic clutch) and his advice was to get a stouter driveline center support maybe off a c4500. Thats why I did a search and found the one piece driveshaft TSB. I've also heard all the stuff about the dual mass flywheel. The company that's using my truck as a test mule found out what they wanted to know. A stock ZF 6-speeder can't handle over 100 HP. It's gonna need a stouter clutch and maybe more.
 

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Are you sure it's only good for 100hp? I briefly played with 155 and didn't seem to cause any harm.
 

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Discussion Starter #9
They tell me the box I'm running is 140hp. I run around town all day at 140 with no problem, it's alot of fun and the driveline doesn't seem to mind. The problem is when I hook 9000 lbs to my back bumper. Then the clutch becomes an issue.
 

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I never haul anything when I put my HJ/A on LvL 3 the clutch slips like grease when I accel smartly. The entire clutch, flywheel, pressureplate, et. al. are a piece of crap. My dealer is going to put a tranny cooler on to stop the hard pedal but that won't stop the slippage. The DMF has already been repaced about 4 weeks ago. So far ok but I am not sure it could handle a stouter clutch. I am going to wait and see how CPMac's investigation goes . . . (check other ZF threads).
 

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I thought for sure they didnt put a one piece on the ZF's. Do you have a pic?


I had the shudder problem too when taking off from 0-~15.


It was driveshaft wobble. I helped this by putting a spacer (just a 11 inch piece of straight stock) about 3/8 in under the carrier bearing. It helped. If I were to go lower, it would have completly gotten rid of it, but I use max payload quite often, and I was afraid that any lower would be bad.


The goal here is to make the two shafts straight as possible.


ColoradoKid told me that the driveshafts of the Allison and the ZF are very different. The ZF's shaft is much beefier, and has larger/stronger U joints. Thus you cant put a one piece on it like you can the Allison...
 

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Manny;


Yep, a one piece. No pic since I don't have a dig cam. Some day.. . .


I saw the pic of your carrier bearing spacer.
Next Idea: how about a remote controlled adjustable carrier bearing spacer (RCACBS) for different loads
?


This could be a useful aftermarket product!!!


I have spoken to the ColoKid on the tele. Since he is an engineer (traffic eng - is this an oxymoron term Kid? -
) he should know. Maybe he could help you design the RCACBS product
!


Anyhow, glad you solution worked. This forum has provided a lot of help and info for me since I haven't owned a diesel for 8 years. Hope CPMac can design a solution for my slippage problem.


Cheers,
 

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Ya. That would be great, but if you load it down to 4000 lbs in the bed, you cant get the carrier bearing high enough. The angle goes from a V when unloaded (imagination needed here) to an upside down v when loaded...


Did youf left mess things up? Are there spacers under the rear axle? That seems to aggrivate the problem...
 

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Hey Manny;


The dealer said the tech said that the lift with bigger wheels caused more heat in the tranny and thay was why the pedal got hard and why they are going to do the tranny cooler. BS It is the clutch that is causing the heat an making the hydraulic hot which presses back on the pedal. GM doesn't have a clue on this problem. I am just working to keep this issue in the dealer's face hoping that some day they will have a better clutch.
Yea, right.
I hanve not notice any vibration related to the tranny since they replaced the flexplate (flywheel). The new wheels/tires work perfectly. No vibe and no noise. I really like the lift. All the traffic sees me coming and gets outa my way!!!
 

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Ive heard several times about this hard pedal thing...


Ive never had it once, even after towing through the desert in the summer at 80 for hours on end...


I am getting taller tires in a few thousand when the stockers wear out...
 
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